This invention relates in general to the field of pulsed sources and in particular to frequency pushing stabilization of sources.
Most pulsed sources, including vacuum tube as well as solid-state, will shift in frequency due to changes in power dissipation within the source. These frequency shifts are essentially due to thermal heating which increases as the pulsed source duty cycle is changed and the pulse repetition frequency (PRF) increases. As an example, for an X-band oscillator (10 GigaHertz (GHz)), a typical uncompensated PRF-induced frequency shift can be 4.2 MegaHertz (MHz) for a variation from 0 to 7 kiloHertz (kHz) PRF. This thermal frequency drift may not always be tolerable in the situation of stringent frequency stability requirements.
Typical methods for dealing with frequency stabilization involve the techniques of injection locking, multiplier chains, or phase locked loops. However, these techniques are relatively complex (i.e., require a significant number of component parts), and are relatively large and costly. These classical approaches also typically use Watts (W) of direct current (DC) power, which may be several orders of magnitude beyond what is available for frequency stabilization of a given circuit. Relatively high power consumption and high part count can also substantially lessen overall reliability. Where battery operated systems are used, a large DC power requirement is prohibitive. It is especially difficult to provide for frequency stability in pulsed sources where low cost and small size are significant constraints.
Thus, a practical, economical method for the frequency stabilization of pulsed sources, employing an apparatus which contains relatively few parts, is small, simple to implement and adjust, and which consumes little DC power would be particularly advantageous. It would additionally advantageous to provide for the frequency stabilization method to allow for temperature controlling of components to compensate frequency changes due to ambient temperature changes.